To Kill an Octopus
by Yuki28
Summary: To kill an octopus, you need help from the mafia. Seriously. That's why Sawada Tsunayoshi, Vongola Decimo, will be assigned to teach the students of Class E to do exactly that. (Does that thing even have eight legs?) Collab with SeeUinHell


**Yuki: Hello, humans. So I suddenly wondered what a KHR/AK X-over would be like, so I asked my friend, SeeUinHell, if she would help me write the story and ta da, collab!**

**Hell: Hey, people. This is actually my first multi-chapter story. If you bother to look at the story I already have...DON'T! That was from like half a year ago when I was bad.**

**Yuki: This is my first X-over, Hell's too, so it might not be the best, but I think it's pretty good for a first try.**

**Hell: Read and enjoy, that's what we're supposed to say, right? Reviews are welcome-**

**Yuki: Very welcome.**

**Hell: -So just let us know what you think.**

**Yuki: Katekyo Hitman Reborn and Ansatsu Kyoushitsu don't belong to me or Hell. They belong to Akira Amano and Matsui Yuusei.**

**Summary:** To kill an octopus, you need help from the mafia. Seriously. That's why Sawada Tsunayoshi, Vongola Decimo, will be assigned to teach the students of Class E to do exactly that. (Does he even have eight legs?)

* * *

><p><strong>Chapter 1: Class 3-E<strong>

* * *

><p>"Dame-Tsuna."<p>

Tsuna' head shot up, sudden panic filling him. He was supposed to be doing his paperwork. "I was just resting my eyes!" he blurted.

Reborn's brow raised, unimpressed. It looked rather unnerving on a five year old. But then again, this was Reborn, so who was he to question him? "Tsuna," he drawled (And wasn't that frightening?). Tsuna sat straight. Reborn only called him by name when something was serious. The toddler dropped a manila folder on Tsuna's desk. A shiver went up Tsuna's spine as he saw the glint in Reborn's eyes. "You're doing this." Tsuna feared opening that file now.

But if he didn't…

Tsuna snatched the folder up and flipped it open. Staring back at him was the picture of a yellow...octopus thing. "What?" Tsuna said blankly.

Reborn rolled his eyes. "Read it, Dame-Tsuna." Tsuna started reading the file as directed.

_**Subject-62:**_

_**Description:**_ _Yellow, takes on the appearance of an octopus (number of tentacles unconfirmed)? Beady black eyes, always grinning. No known nose or ears. Chromatophore. Wears fancy graduation robes, accompanied by a matching hat and a tie with the symbol of a crescent moon (From his previous action?)._

_**Personality:**_ _Surprisingly normal. Often takes on a mocking tone. Has unusual interest in pornographic magazines (pervert). For further information, contact Karasuma Tadaomi._

_**Weakness:**_ '_Anti-sensei' material. Further information currently being investigated._

_**Motives:**_ _Has intentions to destroy the earth one year from 28 March 20XX. (Has already destroyed approximately 70% of the Moon as warning.)_

_**Conditions:**_ _Subject demands to be given free reign to teach a class (Class 3-E of Kunugigaoka Junior High School)._

_**Current Strategy: **__Class E is to be trained by Karasuma Tadaomi to learn the skills needed to assassinate Subject. Other professionals and hitman will be hired to attempt to eliminate Subject._

Tsuna didn't need to read anymore. He snapped the folder shut to meet Reborn's calculating eyes.

"I didn't think you'd be so determined to take the job," Reborn commented, watching Tsuna's every movement. "I thought you'd reject the job, and that I'd have to force you to do it."

"I changed my mind," Tsuna stated calmly, picking up his pen to continue doing his paperwork. "I'm willing to accept this."

"Why?"

Tsuna looked up.

"You aren't the type to agree to these things unless you're absolutely sure it is safe," Reborn explained. "So why?"

"I don't like it," Tsuna answered, voice tight. "I don't understand why they have to train kids to be assassins. Their lives shouldn't be taken away like that."

"You forget, Dame-Tsuna," Reborn responded, "That potential is best drawn out from a young age. Mafioso always start training from a young age. You were the same. There's a reason it was decided you be trained as early as possible. You were fourteen at the time."

"Thirteen," Tsuna absently corrected, flinching at the glare Reborn gave him. "But I never had a choice." He ignored Reborn's now smug look. "For me, it was either do or die. If these children are to be trained, I want to make sure they're trained well." He signed another document and then set his pen down, leaning back into his armchair. "I'm aware of how...simpleminded some higher up government members can be. I don't want them to get a class of students killed and cover it up just to save their own reputation."

"I don't care how personal this situation is to you," Reborn said peeking over a stack of paperwork to meet Tsuna's eyes. His gaze was cold and blank, all business. "On a job, your opinions don't matter. Your actions will reflect on your family, but because you are the Vongola Decimo, your actions will reflect on all of Cosa Nostra. You wanted everyone's view of Vongola being the family with the bloodiest history to change, to become more like Primo's vigilante group. Finish the mission the way you believe will help you achieve that dream."

Tsuna was stunned, eyes wide in surprise. "I...Reborn…That...was really cheesy." Tsuna winced at the pain he received immediately after the words left his mouth. "It's true!" Tsuna insisted. His eyes softened. "But thanks. I will."

Reborn smirked, stepping back with a satisfied air around him. "You better." He pulled the brim of his fedora down to shadow his eyes, a smile playing on his lips.

**-To Kill an Octopus-**

Tsuna sighed as he headed for the government building listed in the file he was given. Reborn had promptly kicked Tsuna out of Vongola HQ, shoving him onto a private jet to Japan. Tsuna felt nervous. He was a mafioso. It wasn't normal for mafiosi to just walk through the front gates into a government building. After talking to the receptionist and being directed up to the top floor (Seventh floor), he was arrived in front of two large wooden doors with golden handles. He knocked on them thrice.

"Come in," he heard. He pushed the doors open.

Tsuna entered the room to see a rather fancy looking office room, though not anything close to the Don Vongola's office back at Vongola HQ. There was a rounded desk in the far middle of the room. Sitting behind it was a middle-aged man with carefully combed brown hair and dark brown eyes wearing a standard suit that everyone in the government wore. His arms were propped up on their elbows, fingers laced together. Tsuna noticed a worn out gold ring on his left hand's ring finger and a gold watch on his right wrist. Not counting the fact that Tsuna knew the man was in charge of the military, he could easily tell that the man was wealthy.

"Yama Arato-san," Tsuna greeted with a small bow of his head. Off to the side, Tsuna could see another man with spiky black hair and dark narrow eyes also wearing a suit. He was watching Tsuna like a hawk. "I believe you requested some...help with a certain situation."

Yama nodded, brown eyes hardening. "I don't like asking criminals for help, but I'm willing to lower myself for such a problem."

Tsuna frowned slightly. "I understand that my kind doesn't have the best morals, but we have better morals than actual criminals, sir."

Yama's lips thinned. "If that's what you believe. Sawada Tsunayoshi, was it? I've read your file. It's hard to believe you've become this sort of person."

"What I believe," Tsuna responded coolly. "Is that we were here to discuss what I was hired for, not my personal life."

"I apologize," Yama didn't sound apologetic at all. "Then back onto topic. This is Karasuma Tadaomi." He gestured at the black haired man in the room. "He is currently in charge of observing Subject-62. You will be working alongside him for the duration of your...mission." Karasuma gave him a curt nod, and Tsuna returned it. "Am I to assume that you understand the fact that you are working for us is not to be leaked to _anyone?_"

Tsuna smiled wryly inside. "Of course, sir. The same could be said from my side." Yama stiffened and glared. _Point for me_, Tsuna cheered inwardly.

"That is all," Yama said tightly. "You are dismissed."

Tsuna held the urge to snort. That Yama thought he was in charge of Tsuna. The old man didn't even know Tsuna's rank in the mafia! But Tsuna was undercover as a solo hitman, so he couldn't talk back if he didn't want to be fired. Without another sound, Tsuna left the room, letting the door close behind him softly.

**-To Kill an Octopus-**

Tsuna didn't like him.

Asano Gakuhou.

Tsuna had been told to meet the board chairman of Kunugigaoka Junior High School. Tsuna knew immediately that he wouldn't like the man. His presence itself bothered Tsuna. The man just stood there, with his auburn colored hair gelled back and a poster smile on his face. Yet he was able to make Tsuna's intuition react so strongly. The guy had secrets, everyone did, but this man seemed to have hidden intentions, ones that no normal person would ever think of. Tsuna's seen people like him before, people who wanted, _needed,_ to be in control. But this man was better than them. He had a mentality even better than those in the mafia. This man knew exactly what was needed to be and stay on top and control the ones under him. And this man, Asano Gakuhou, stood before him now.

"So you are going to accompany...Koro-sensei," the name was said in distaste. "In teaching Class 3-E?" Asano didn't like Koro-sensei then, but kept that fake smile for appearances sake.

"Yes," Tsuna answered, thinking about how easily a normal person would've been tricked by that smile. "I was assigned to that class by..." Tsuna momentarily pondered how much he should reveal. "The government."

Something alit in Asano's eyes. "Then you are aware of the special circumstances of that class and not just a normal teacher."

Tsuna nodded slowly. "I have been trained in hand to hand combat. However, my purpose here is not to slay...Koro-sensei, was it? I've been told to observe his teaching methods and assist or correct him if necessary."

"I see." Asano's lips twitched downward. His type of person also hated those stubbornly loyal to someone else, as Tsuna might've seemed to the government. Tsuna would let him assume whatever he wanted if it kept Asano from attempting to manipulate him.

"If you'll excuse me," Tsuna bowed his head down slightly to imply that he had nothing else to say.

"You're dismissed." Tsuna was starting to hate that line. He exited only to blink in surprise when he saw Karasuma waiting for him against the wall outside the room.

"Karasuma-san," Tsuna greeted. "It's been a while."

Karasuma stared at him. "It's been a few hours."

"Exactly."

Karasuma stared at him for a split second longer before shaking his head in reluctant amusement. "Anyways, I will show you to Class E's classroom. It isn't really a...convenient place to go to."

Tsuna blinked, confused. It was just a classroom, wasn't it? Somewhere in the school?

He was wrong.

Class 3-E's classroom turned out to be a hut on a mountain.

Tsuna examined the room he had just entered. The room was dilapidated, simple wooden walls not even painted over with holes in them, and old desks also made of wood. Some of the desks' surfaces weren't even flat. The blackboard seemed to be the object in the best condition in the room.

"You're the one that's going to join us in teaching the class?" a voice chirped. Tsuna blinked at the one who spoke. It was the yellow octopus from the pictures in the file he received. The octopus's grin was more unnerving in person. "You can call me Koro-sensei," Koro-sensei said, holding out a...tentacle for Tsuna to shake.

Tsuna hesitantly shook it. "I'm Sawada Tsunayoshi. I'll...be in your care from now on so please take care of me," he said with a slightly nervous smile. He had never taught anyone before. This being a mission just added to the pressure. "It's a...a pleasure to meet you, Koro-sensei."

Koro-sensei's grin seemed to widen slightly. "The same to you, Sawada-sensei. Why don't you get comfortable while waiting for the students to arrive?"

Tsuna nodded curtly, pulling his hand back as Koro-sensei returned to his desk. Out of the corner of his eye, he saw Karasuma nod his head towards the hallway. Tsuna followed him out of the classroom.

"So?" Karasuma asked once the door closed behind them in a small voice. "What do you think?"

"I'm not sure yet," Tsuna admitted honestly. "But he is rather...interesting in appearance."

Karasuma nodded in understanding. "I see. You can use the time before the kids arrive to get used to the area if you'd like."

"Thank you," Tsuna said.

And that's what Tsuna did. He wandered the perimeters of the small hut (more like shack) for about half an hour, noting anything of importance, like the open field, any particularly large trees, or potholes that might hinder him in the future. For the next half hour, he skimmed the students' profiles he had been provided with. He memorized names and appearances, not taking note of anything else because he believed the students should be the ones to tell any other personal information.

The students started to trickle up the mountain soon after. Tsuna had watched from one of the larger trees he found, keeping track of their personalities and their attitude towards others. It was only after Karasuma came to retrieve him that he got down. Karasuma wanted him to introduce himself to the class. Tsuna inwardly grimaced, not looking forward to being watched by about thirty pairs of eyes.

As he entered the classroom, Tsuna glanced over the students. They were watching him, just like he had expected. But really. They were only fifteen or sixteen. Why...Just why were they condemned to this fate?

"Are you alright?"

Tsuna flicked his gaze over to Karasuma at his right. "Yes," Tsuna answered curtly. He turned back towards the class. "Hello," Tsuna started. "I am Sawada Tsunayoshi. I will be assisting this class in," Tsuna's gaze wandered over to the yellow octopus reading inappropriate magazines. He let a small sigh escape. "Necessary skills for the rest of this year." The class was silent, scrutinizing him. "...Any questions?"

A few hands shot up. Tsuna nodded towards a black pony-tailed girl, Yada Touka.

"Are you going to try to kill Koro-sensei?"

Tsuna didn't look towards said teacher. "Indirectly," he answered shortly. He turned towards a wavy haired girl, Kurahashi Hinano, meeting her gaze.

"Er, what was your job before this?"

"I am a hitman," Tsuna turned towards the next student with their hand up as soon as the girl's eyes started to widen. This was a turquoise haired girl, Kayano Kaede.

"Uhm, What exactly are you going to teach?"

Tsuna smiled a smile that held no warmth. "Anything necessary."

"Anything?" A red haired boy called out. That was Akabane Karma.

Tsuna met his gaze. The kid was challenging him. "Anything," Tsuna answered firmly.

"So you're teaching us to kill, right?"

"Oi, are you after the money too?!"

"How old are you anyways?"

"Are you going to teach us how to make bombs?"

"What about knife throwing?"

Tsuna noticed a hand raised off to the side of the classroom. "Chiba Ryounosuke-kun," Tsuna raised his voice over the students'. "What's your question?" The class immediately silenced, turning their attention towards said boy. The black haired teen fidgeted under their gazes, hair covering his face now proving to be useful.

"We...Are we going to learn how to use different types of guns?" he asked quietly.

Tsuna hid a genuine smile. "Yes," he answered. "If you have any preference, let me know later on. Any other questions?" The classroom stayed silent. "Good. Today, I'll only be observing to see how things work around here. If you have problems with that, I don't care." Seeing the students gapes were worth it.

**-To Kill an Octopus-**

The guy just stood there. Watching them. It was kind of creepy actually. Karma nudged Nagisa lightly, turning the blue haired boy's attention away from their new teacher. "What is it, Karma-kun?" Both of them struck their arm downwards, gripping the anti-sensei knife tightly, as directed by Karasuma-sensei.

"What do you think of him?" Karma asked, jerking his chin towards Sawada-sensei standing at the side of the field.

"We've only known him for an hour," Nagisa chided lightly.

Touka suddenly appeared beside them. "How old do you think Sawada-sensei is?" she asked with a sly smile.

"Nineteen years old," Ritsu's mechanical voice came from Nagisa's pocket.

The three students were taken aback.

"He's an assassin at that young of an age?!" Touka whispered in shock.

He couldn't have heard them speaking; they were too far, but Sawada-sensei turned towards them as if he knew they were talking about him.

Karma tossed a smirk over towards Sawada-sensei. Sawada-sensei surprisingly smiled wryly back. Karma turned back to Nagisa, who had taken his phone out. "What else do you have on him, Ritsu?"

"His hometown is Namimori, Japan. He graduated from Namimori High School," Ritsu continued.

"Did he go to college?" Touka asked when Ritsu didn't continue talking about his education.

"Records show that he flew to Italy," Ritsu replied. "There is no known information of Sawada-sensei entering college in Japan."

"That's surprising," Nagisa said. "You would think that the principal would only allow people with exceptional education to teach."

"Well he probably doesn't care," Kaede commented, joining their conversation. "I mean, we're Class E," she said bitterly. "It doesn't matter if our education is good or bad."

"We don't have time to worry about our education anyways," Karma said with a shrug. "We're busy trying to kill the guy who says he's going to destroy the world. Why would our grades matter?"

"Stop chatting!" Karasuma-sensei barked, interrupting them. They jolted back into position, continuing their downward strike exercise.

**-To Kill an Octopus-**

Irina had arrived late. She had been held up by...other things, such as going out to bars despite it being early in the afternoon. She hadn't been on actual missions in a while, so she liked to play the men at bars, attracting them then tossing them away. She took pleasure in seeing men knocked down a few pegs. At least she made it on time for her own lessons. However, she didn't get the notification about the newcomer.

"Who's the new kid?" Irina asked Karasuma when she entered, looking over at said 'kid' at the other end of the room.

"He's not a new student," Karasuma answered, not looking up from the file he was reading. "He's an assistant teacher and will be helping Koro-sensei teach the academic subjects, as well as helping us teach the assassination subjects."

Irina gave him an unconvinced look. "Really? He looks like a wet behind the ears brat."

"You of all people should know not to judge people by their looks. Besides, he's from the-" Karasuma lowered his voice. "Mafia."

Irina only smirked. "He seems fun to play with," she said, ignoring Karasuma's words. "Let's see what he can do." Getting up, she walked towards the brown haired young man with the seductive aura she always used for work.

"Hey there…"

The young man turned towards her, giving her a warm smile. "Hello, you must be the other teacher here. I'm Sawada Tsunayoshi."

"Well then, Tsunayoshi-kun," she purred his name out, earning an uncomfortable fidget. "I'm Irina Jelavic, or Jelavic Irina."

"Bitch-sensei!" Karma called out from the back of the room with a mischievous smirk. "You're never going to succeed, you know! Stop trying!"

Irina's eye twitched. "You little brat!" she growled angrily. She fought the urge to go beat the kid up in order to smile sweetly at Sawada. "Ignore them, Tsunayoshi-kun."

Sawada only blinked at her. "Tsuna is fine, Jelavic-san."

Irina inwardly frowned. The boy wasn't reacting as expected at all. She kept smiling. "Why don't we do something together after class? I guarantee it'll be fun," she winked.

Sawada furrowed his brows, looking upset. "I'm sorry Jelavic-san, but I have no interest in romance. I'd appreciate it if you didn't flirt with me."

"Hah! You got re-jec-ted, Bitch-sensei!" Now Irina openly glared at Karma. She turned back to Sawada with a cool expression. "Well, it was worth a try," she said offhandedly. "You're not so bad, Tsunayoshi-kun."

"Just Tsuna is fine," Sawada-Tsuna repeated politely. "And thank you for the compliment." He glanced at his watch. "I'm sorry, but I must be going soon. Goodbye." Without a glance back, he was out the door.

Irina watched him leave, before turning onto a certain someone who had pissed her off the whole conversation. "Karma, you little brat!"

The red haired menace stuck his tongue out at her, dashing out of the room with a snicker.

**-To Kill an Octopus-**

Tsuna grimaced as he settled into a comfortable armchair. It had been a long and tiring day even though he did nothing. It was probably the fact that he had to deal with so many authority figures. He tilted his head from side to side, stretching his neck and yawning. He just hoped the kids wouldn't be that hard to teach, but knowing his luck...they probably were.

Tsuna almost jumped out of seat when a familiar ringing was heard. He fumbled for his phone and answered the call hurriedly once he saw the caller ID. "H-Hello? Reborn?"

"_Dame-Tsuna, did I just hear you stutter?"_

"No!" Tsuna yelped. "But...why did you call?"

"_Stupid, I had to make sure you didn't mess anything up. How was it so far?"_

Tsuna calmed down. "Well, Koro-sensei isn't an evil mastermind villain. That's more like the principal. Karasuma-san is easy to get along with, and Jelavic-san is rather...Well, I haven't known her for even longer than ten minutes, but she tried to seduce me. It doesn't really leave the best impression, but I know she was only trying to test me."

"_Seems like you've had quite the day,"_ Reborn commented dryly. "_Good luck teaching a bunch of brats. I'm sure you'll have trouble. I did with you."_ He hung up.

Tsuna slumped down in his seat, groaning.

**Chapter Fin.**

* * *

><p><strong>Yuki: So what did you all think?<strong>

**Hell: Good or bad?**

**Yuki: Was Bitch-sensei POV good? Honestly, that was a bit hard to write. Should we add more from students' POV?**

**Hell: By the way, this takes place sometime after chapter 23 and before chapter 25 of Ansatsu Kyoushitsu.**

**Yuki: Reviews, follows, and favorites are very welcome. Let us know what you liked or disliked.**


End file.
